Chemical mechanical polishing pad

Abstract

A polishing pad for use in chemical mechanical polishing of a semiconductor substrate is described. The polishing pad comprises a substantially flat disk having a polishing surface for contacting the substrate. The polishing surface, which has a central region and a peripheral region, is segmented by a set of substantially parallel linear grooves. The grooves include central grooves which traverse the central region of the polishing surface, and peripheral grooves which traverse the peripheral region of the polishing surface. The central grooves have central groove dimensions, including a central groove width and pitch. The peripheral grooves have peripheral groove dimensions, including a peripheral groove width and pitch. At least one of the central groove dimensions, i.e. the width or the pitch, is different from the corresponding peripheral groove dimension. This difference in groove dimensions from the center to the edge of the polishing surface introduces a difference in the polishing surface area provided near the peripheral region as compared to the central region of the pad. As the polishing pad spins in relation to the substrate being processed, the variation in polishing surface area across the polishing surface results in a difference in the rate of material removal near the periphery of the substrate as compared to the rate of material removal near the substrate center. Thus, by providing a variation in the width or pitch of the grooves across the polishing surface of the pad, the invention provides for a corresponding radial variation in the polishing rate distribution across the polishing surface.

What is claimed is:  
     
       1. A polishing pad for use in chemical mechanical polishing of a substrate, the polishing pad comprising a substantially flat disk having a polishing surface for contacting the substrate, the polishing surface having a central region and a peripheral region, the polishing surface segmented by a first set of substantially parallel linear grooves directed in a first direction and a second set of substantially parallel linear grooves directed in a second direction that is different from the first direction, 
       the first set of substantially parallel linear grooves comprising: 
       first central grooves having first central groove dimensions including a first central groove width and pitch, the first central grooves traversing the central region of the polishing surface, and  
       first peripheral grooves having first peripheral groove dimensions including a first peripheral groove width and pitch, the first peripheral grooves traversing the peripheral region of the polishing surface,  
       where at least one of the first central groove dimensions is different from a corresponding first peripheral groove dimension, and  
       the second set of substantially parallel linear grooves comprising: 
       second central grooves having second central groove dimensions including a second central groove width and pitch, the second central grooves traversing the central region of the polishing surface, and  
       second peripheral grooves having second peripheral groove dimensions including a second peripheral groove width and pitch, the second peripheral grooves traversing the peripheral region of the polishing surface,  
       where at least one of the second central groove dimensions is different from a corresponding second peripheral groove dimension,  
       where each of the grooves completely crosses the polishing pad and has a uniform width. 
     
     
       2. The polishing pad of  claim 1  wherein the first direction is substantially perpendicular to the second direction. 
     
     
       3. The polishing pad of  claim 1  wherein first central groove width is greater than the first peripheral groove width, and the second central groove width is greater than the second peripheral groove width. 
     
     
       4. The polishing pad of  claim 3  wherein first central groove pitch is substantially equivalent to the first peripheral groove pitch, and the second central groove pitch is substantially equivalent to the second peripheral groove pitch. 
     
     
       5. The polishing pad of  claim 1  wherein first central groove pitch is less than the first peripheral groove pitch, and the second central groove pitch is less than the second peripheral groove pitch. 
     
     
       6. The polishing pad of  claim 5  wherein first central groove width is substantially equivalent to the first peripheral groove width, and the second central groove width is substantially equivalent to the second peripheral groove width. 
     
     
       7. A polishing pad for use in chemical mechanical polishing of a substrate, the polishing pad comprising a substantially flat disk having a polishing surface for contacting the substrate, the polishing surface having a central region and a peripheral region, the polishing surface segmented by a first set of substantially parallel linear grooves directed in a first direction and a second set of substantially parallel linear grooves directed in a second direction that is different from the first direction, 
       the first set of substantially parallel linear grooves comprising: 
       first central grooves having first central groove dimensions including a first central groove width and pitch, the first central grooves traversing the central region of the polishing surface, and  
       first peripheral grooves having first peripheral groove dimensions including a first peripheral groove width and pitch, the first peripheral grooves traversing the peripheral region of the polishing surface,  
       where at least one of the first central groove dimensions is different from a corresponding first peripheral groove dimension,  
       the second set of substantially parallel linear grooves comprising: 
       second central grooves having second central groove dimensions including a second central groove width and pitch, the second central grooves traversing the central region of the polishing surface, and  
       second peripheral grooves having second peripheral groove dimensions including a second peripheral groove width and pitch, the second peripheral grooves traversing the peripheral region of the polishing surface,  
       where at least one of the second central groove dimensions is different from a corresponding second peripheral groove dimension,  
       an intermediate region disposed between the central region and the peripheral region, wherein: 
       the first set of substantially parallel linear grooves further comprise first intermediate grooves having first intermediate groove dimensions including a first intermediate groove width and pitch, the first intermediate grooves disposed between the first central grooves and the first peripheral grooves, and traversing the intermediate region of the polishing surface, where at least one of the first intermediate groove dimensions is different from a corresponding first central groove dimension and corresponding first peripheral groove dimension, and  
       the second set of substantially parallel linear grooves further comprise second intermediate grooves having second intermediate groove dimensions including a second intermediate groove width and pitch, the second intermediate grooves disposed between the second central grooves and the second peripheral grooves, and traversing the intermediate region of the polishing surface, where at least one of the second intermediate groove dimensions is different from a corresponding second central groove dimension and corresponding second peripheral groove dimension.  
     
     
       8. The polishing pad of  claim 7  wherein: 
       the first intermediate groove width is different from the first central groove width and the first peripheral groove width, and  
       the second intermediate groove width is different from the second central groove width and the second peripheral groove width.  
     
     
       9. The polishing pad of  claim 8  wherein: 
       the first intermediate groove width is less than the first central groove width and greater than the first peripheral groove width, and  
       the second intermediate grove width is less than the second central groove width and greater than the second peripheral groove width.  
     
     
       10. The polishing pad of  claim 7  wherein: 
       the first intermediate groove pitch is different from the first central groove pitch and the first peripheral groove pitch, and  
       the second intermediate groove pitch is different from the second central groove pitch and the second peripheral groove pitch.  
     
     
       11. The polishing pad of  claim 10  wherein: 
       the first intermediate groove pitch is greater than the first central groove pitch and less than the first peripheral groove pitch, and  
       the second intermediate groove pitch is greater than the second central groove pitch and greater less the second peripheral groove pitch.  
     
     
       12. A polishing pad for use in chemical mechanical polishing of a substrate, the polishing pad comprising a substantially flat disk having a polishing surface for contacting the substrate, the polishing surface having a central region and a peripheral region, the polishing surface segmented by a set of substantially parallel linear grooves, the grooves comprising: 
       central grooves having central groove dimensions including a central groove width and pitch, the central grooves traversing the central region of the polishing surface, and  
       peripheral grooves having peripheral groove dimensions including a peripheral groove width and pitch, the peripheral grooves traversing the peripheral region of the polishing surface,  
       where at least one of the central groove dimensions is different from a corresponding peripheral groove dimensions,  
       where each of the grooves completely crosses the polishing pad and has a uniform width.  
     
     
       13. The polishing pad of  claim 12  wherein central groove width is greater than the peripheral groove width. 
     
     
       14. The polishing pad of  claim 13  wherein central groove pitch is substantially equivalent to the peripheral groove pitch. 
     
     
       15. The polishing pad of  claim 12  wherein central groove pitch is less than the peripheral groove pitch. 
     
     
       16. The polishing pad of  claim 15  wherein central groove width is substantially equivalent to the peripheral groove width. 
     
     
       17. A polishing pad for use in chemical mechanical polishing of a substrate, the polishing pad comprising a substantially flat disk having a polishing surface for contacting the substrate, the polishing surface having a central region and a peripheral region, the polishing surface segmented by a set of substantially parallel linear grooves, the grooves comprising: 
       central grooves having central groove dimensions including a central groove width and pitch, the central grooves traversing the central region of the polishing surface,  
       peripheral grooves having peripheral groove dimensions including a peripheral groove width and pitch, the peripheral grooves traversing the peripheral region of the polishing surface,  
       where at least one of the central groove dimensions is different from a corresponding peripheral groove dimension, and  
       an intermediate region disposed between the central region and the peripheral region, and wherein the set of substantially parallel linear grooves further comprise intermediate grooves having intermediate groove dimensions including an intermediate groove width and pitch, the intermediate grooves disposed between the central grooves and the peripheral grooves, and traversing the intermediate region of the polishing surface, where at least one of the intermediate groove dimensions is different from a corresponding central groove dimension and a corresponding peripheral groove dimension.  
     
     
       18. The polishing pad of  claim 17  wherein the intermediate groove width is different from the central groove width and the peripheral groove width. 
     
     
       19. The polishing pad of  claim 18  wherein the intermediate groove width is less than the central groove width and greater than the peripheral groove width. 
     
     
       20. The polishing pad of  claim 17  wherein the intermediate groove pitch is different from the central groove pitch and the peripheral groove pitch. 
     
     
       21. A polishing pad for use in chemical mechanical polishing of a substrate, the polishing pad comprising: 
       a substantially flat disk of abrasive material, the disk having a polishing surface for contacting the substrate, the polishing surface constructively divided into annular regions and segmented by orthogonal linear grooves,  
       the grooves having widths and pitches, where the widths and pitches of the grooves in the annular regions of the polishing pad selectively vary from one annular region to another annular region of the polishing pad,  
       where each of the grooves completely crosses the polishing pad and has a uniform width.